1. Technical field
The invention relates to a method for the coating of individual items, where each item has two substantially plane and mutually parallel sides, and comprising two process steps where in a first step the item is sprayed with coating when it passes a spray box, followed by the second step where the coating is hardened, and where at least two mutually adjoining sides of the item are treated in both steps.
The invention also relates to an apparatus for use in the coating of individual items, where each item has two substantially plane and mutually parallel sides, said apparatus having a spray box with an entry end and an exit end for the items, and with spraying means for the application of coating on at least two mutually adjoining sides of an item. The term "coating" also includes varnish, paints, primers. lacquer and the like.
2. State of the Art
A method and an apparatus as disclosed above, hereinafter called the vacuum technique is known, and the varnishing or lacquering is effected by leading the items or work pieces transversely through a closed container with recirculation of the surplus coating. Around the entry the exit ends there are seals which ensure that coating does not escape to the surroundings, which is of special significance when processing with toxic coatings which harden in ultraviolet light. The disadvantages of the vacuum principle are that only items having a flat profile and without any form of cavity work, discontinued grooves or decorative milling on one or more sides can be treated. Moreover, the ends of the items cannot be varnished, and minimum lengths of possible items lie in the magnitude of 400-500 mm. This is a considerable disadvantage when processing items of wood for furniture production where there is often need for shorter items.
In another known technique whereby the coating is applied by spraying with a traverse spray where the whole item with the spray gun is placed in a larger box or spray enclosure. In addition to the fact that only 20-25% of the surplus coating can be recovered, the cleaning of the spray area and the inside of the box creates problems, as the cleaning takes a long time and, connection and the use of coating hardened by ultraviolet light, it is detrimental to the health of the personnel who are required to carry out the cleaning of the box.
Finally, it can be mentioned that GB A 2,201,104 describes the application of primers and paint on cement tiles, where the tiles are fed past the spray stations resting on a conveyor. After each spray station, the applied layer of coating is hardened under the influence of infrared light. However, the document deals only with an application on one side of the item, as only the side facing upwards and away from the conveyor can be treated.